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https://issues.apache.org/jira/browse/HIVE-20264?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16577033#comment-16577033
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Sankar Hariappan commented on HIVE-20264:
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Test failures are irrelevant. Patch 01 committed to branch-3.
> Bootstrap repl dump with concurrent write and drop of ACID table makes target
> inconsistent.
> -------------------------------------------------------------------------------------------
>
> Key: HIVE-20264
> URL: https://issues.apache.org/jira/browse/HIVE-20264
> Project: Hive
> Issue Type: Sub-task
> Components: HiveServer2, repl
> Affects Versions: 4.0.0, 3.2.0
> Reporter: Sankar Hariappan
> Assignee: Sankar Hariappan
> Priority: Major
> Labels: DR, pull-request-available, replication
> Fix For: 4.0.0, 3.2.0
>
> Attachments: HIVE-20264.01-branch-3.patch, HIVE-20264.01.patch,
> HIVE-20264.02.patch
>
>
> During bootstrap dump of ACID tables, let's consider the below sequence.
> - Get lastReplId = last event ID logged.
> - Current session (Thread-1), REPL DUMP -> Open txn (Txn1) - Event-10
> - Another session (Thread-2), Open txn (Txn2) - Event-11
> - Thread-2 -> Insert data (T1.D1) to ACID table. - Event-12
> - Thread-2 -> Commit Txn (Txn2) - Event-13
> - Thread-2 -> Drop table (T1) - Event-14
> - Thread-1 -> Dump ACID tables based on current list of tables. So, T1 will
> be missing.
> - Thread-1 -> Commit Txn (Txn1)
> - REPL LOAD from bootstrap dump will skip T1.
> - Incremental REPL DUMP will start from Event-10 and hence allocate write id
> for table T1 and drop table(T1) is idempotent. So, at target, exist entries
> in TXN_TO_WRITE_ID and NEXT_WRITE_ID metastore tables.
> - Now, when we create another table at source with same name T1 and
> replicate, then it may lead to incorrect data for readers at target on T1.
> Couple of proposals:
> 1. Make allocate write ID idempotent which is not possible as table doesn't
> exist and MM table import may lead to allocate write id before creating
> table. So, cannot differentiate these 2 cases.
> 2. Make Drop table event to drop entries from TXN_TO_WRITE_ID and
> NEXT_WRITE_ID tables irrespective of table exist or not at target.
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